1. Field of the Invention
This invention relates generally to devices used to collect fluid samples from patients. More specifically, this invention relates to a device which utilizes a holder having a double-ended needle that can be retracted into the holder when a cap of the holder is closed. The invention also relates to a method of collecting a fluid sample with the device as well as a method of making the device. The invention also relates to a blood sample collection device that automatically retracts the double-ended needle into the holder after a cap closes off the open end of the holder
2. Discussion of Background Information
Prevention of needle sticks is of paramount concern in the healthcare industry because of serious and deadly risk factors associated with AIDS and other serious communicable diseases. Typical blood collection devices utilize a needle inserted into a patient's vein so as to draw blood through the needle into an associated separate collection reservoir. Accidental needle sticks from previously used needles can occur during the fluid withdrawing process and subsequent handling and disposal operation. Until such used medical devices are destroyed, they remain a risk to those handling them.
Devices used for blood sampling are well know and include a collection device sold under the trademark Vacutainer® by Becton Dickinson Corporation. This device has a tubular syringe-like body with a needle in the front end, part of which extends back into a tubular syringe-like shell. Part of the needle extends externally for punching the skin. An evacuated collection tube with a rubber stopper is placed into the open back of the syringe-like shell with the rubber stopper against the internal end of the needle. After the skin is punctured, the collection tube is pushed forward to cause the needle to enter the evacuated tube. Vacuum helps draw blood into the collecting tube. When a sufficient sample has been obtained, the collecting tube and the stopper are simply withdrawn from the tubular shell and sent to the laboratory. This particular device has a permanently extended needle and an opening in the back for the collection tube which remains open after the collection tube is removed, leaving small quantities of blood and an internally exposed needle.
Retractable medical devices which are used for collecting fluid samples from patients are also known. An early example of such a device is U.S. Pat. No. 4,813,426 which employs a mechanically translatable insert holding a double-ended needle. This device has a position which compresses a spring portion of the holder. When buttons extending from opposite sides of the outer tube are compressed, the needle carrier can be mechanically moved to the position of us or to a rearward safe position. U.S. Pat. No. 4,838,863 describes a spring loaded double ended needle carrier in a T-shaped housing having an opening behind for the sample tube. The needle holder is locked in a use position with a removable pin which is withdrawn to retract the needle. Alternately, breakable tabs on the needle holder extend laterally under a shelf with pins which may be pushed down when the sample tube is inserted to fracture the breakable tabs thereby releasing the needle holder which is withdrawn into the interior as the sample tube is removed. Subsequently, a cap is provided to close the back. Allard does not explain how one could assemble the device without making the outer body in two or more pieces.
Other devices attach the double ended needle to a partially withdrawable plunger with an opening in back for the sample tube. U.S. Pat. No. 5,423,758 to shaw, the disclosure of which is hereby expressly incorporated by reference in its entirety, utilizes a tubular outer body with a partially movable plunger. The plunger has a separable needle holding portion for a double ended needle and an opening in the back of the plunger for a sample tube. It utilizes a two position end cap from which the sample tube extends. The plunger is used to position and retract the needle assembly. U.S. Pat. No. Re 39,107 to shaw, the disclosure of which is hereby expressly incorporated by reference in its entirety, similarly utilizes a tubular outer body with a partially movable plunger. The plunger has a separable needle holding portion for a double ended needle and an opening in the back of the plunger for a sample tube. It utilizes a two position end cap from which the sample tube extends. The plunger is used to position and retract the needle assembly.
The invention aims to improper devices of the type disclosed in U.S. Pat. Nos. 5,423,758 and Re 39,107 to shaw by providing a releasable locking connection between the plunger and the needle holding portion and/or by causing the connection between these two members to release when the plunger experiences pivoting movement.
A conventional blood collection device of the type described above is shown in FIGS. 1-10 wherein the device 1 has an outer sleeve member 2 which includes a proximal end 2a which is configured to allow an external needle N of a double-ended needle member or holder 3 to pass therethrough and a distal end 2b which can be closed off by a cap 5. The needle holder 3 has an outer circumferential surface OCS which frictionally engages with an inner circumferential surface ICS of a proximal end of an inner sleeve 4. The device 1 also includes a spring 6 which functions to move the needle holder 3 when the outer circumferential surface OCS of the needle holder 3 no longer frictionally engages with the inner circumferential surface ICS of the proximal end of the inner sleeve 4. As is shown from FIG. 4, it is believed that the device 1 functions as follows: once a user moves the cap 5 to the closed position, the sleeve 4 is caused to move axially in the proximal direction, which, in turn, causes the outer circumferential surface OCS of the needle holder 3 to disengage from the inner circumferential surface ICS of the proximal end of the inner sleeve 4. The spring 6 is then free to move the needle holder 3 within the sleeve 4 in a distal direction which ensures that the needle holder 3 is fully and safely arranged within the device 1. The device 1 can then be safely handled and discarded.